Two New Species of Resinicolous Chaenothecopsis (Mycocaliciaceae) from Western North America

Abstract

Chaenothecopsis sitchensis and Chaenothecopsis tsugae (Ascomycota, Mycocaliciaceae) are described as new from western North America. Both species grow on conifer resin in wet temperate forests. While they have so far only been collected from Oregon, they may have wide distributions in the Pacific Northwest. Both species occur in specialized microhabitats and can be difficult to find. The genus Chaenothecopsis Vain (Ascomycota, Mycocaliciaceae), is characterized by rather small, non-septate or 1-septate ascospores produced in well stalked or sessile ascomata (Schmidt 1970; Tibell 1984; Titov & Tibell 1992). Like other members of the Mycocaliciaceae they have active ascospore dispersal and a well-developed apical apparatus in the asci. Chaenothecopsis species are either saprobic or parasitic and they associate with algae only as parasymbionts of lichens or parasites of lichens or free-living algae. A number of Chaenothecopsis species occur exclusively on the exudate of vascular plants (Tibell & Titov 1995). Most of these fungi grow on the resin of coniferous trees, and they have been recorded from a variety of hosts, including species of Abies, Larix, Picea, and Pinus. Most species of resinicolous Chaenothecopsis have so far only been reported from temperate forests of East Asia. However, they have a long evolutionary history, as exemplified by a specimen in amber dating back to over 20 million years ago (Rikkinen & Poinar, pers. comm.). During recent field work in western North America, I collected material of several undescribed Chaenothecopsis species on conifer resin. Two of these are described below. Measurements are given as (minimum) mean + s.d. (maximum), or as more intuitive estimates of common ranges. Subjects for all measurements were chosen arbitrarily but without preconceived bias. For ascus and spore measurements a precision of 0.5 psm was used; for capitulum diameter and stalk width a precision of 25 pam was used, and for ascomata height a precision of 0.1 mm was used. Ascomata height, capitulum diameter, and stalk width were measured from dry ascomata under incident light. All other measurements were made from sections mounted in water. CHAENOTHECOPSIS SITCHENSIS Rikkinen, sp. nov. (FIGs. 1-2) Supra exudatum coniferarum, algae in substrato non absunt. Ascomata satis variabilia, vulgo magna, (1.2)2.05.2(16.0) mm alta. Capitulum lenticulare vel subhemisphericum, nigrum. Stipes longissimus, gracilis, rectus vel flexuosus, nigra vel viridula. Omnes partes apotheciorum K+ luteo-virides, dissolvens. Asci magna, 50.0-60.0 x 3.5-4.5 pm, cylindrici. Sporae uniseptatae, anguste ellipsoideae ad cylindricae, pallide brunneae, (7.5)8.010.2(11.5) x (3.0)3.1-3.7(4.0) pm, ornamento minuto